1. Field of the Invention
The invention relates to ball grid array (BGA) devices, more particularly to a contactor system adapted for use when testing BGA devices.
2. Description of the Related Art
Ball grid array (BGA) packages are high pin count integrated circuit packages that are widely used in surface mounting applications. Referring to FIG. 1, a known BGA device 1 includes a semiconductor device disposed on a dielectric insulating substrate 11 that is formed with circuit traces (not shown) for electrical connection with the semiconductor device 10. An array of solder balls 12 that are formed from tin is provided on a bottom surface of the insulating substrate 11 and is connected electrically to the circuit traces to serve as electrical contacts for the BGA device 1. In the mass production of BGA devices 1, a number of insulating substrates 11 are initially interconnected to form a large insulating block. After the circuit traces are formed, the insulating block is subsequently cut to form the individual insulating substrates 11, thereby resulting in exposed conductive contacts on the periphery of each insulating substrate 11.
BGA devices 1 are usually tested for defects during the production stage. FIGS. 2 and 3 illustrate a known contactor system 2 suitable for testing BGA devices 1. The contactor system 2 includes a testing board 20 provided with a testing circuit layout that is connected to a testing apparatus (not shown), and a socket 21 formed from an insulator material and retained on the testing board 20 via a mounting seat 24 that is fixed on the testing board 20. The socket 21 is formed with a receiving space 210 that opens upwardly. Guide members 211 project inwardly from the socket 21 into the receiving space 210. The socket 21 has a contactor plate 212 disposed at a bottom end of the receiving space 210 and formed with a plurality of apertures 213 that are registered with the solder balls 12 of the BGA device 1 that is to be tested. Spring probes or pogo pins 22 are received in the apertures 213. A surface mount matrix 23 is clamped between the contactor plate 212 and the testing board 20. The surface mount matrix 23 interconnects the pogo pins 22 and the testing circuit layout on the testing board 20. The pogo pins 22, in turn, interconnect the BGA device 1 and the surface mount matrix 23.
When testing the BGA device 1 for defects, the BGA device 1 is loaded into the receiving space 210 cf the socket 21 via the open top of the latter so as to enable the solder balls 12 to contact the pogo pins 22. The guide members 211 facilitate proper positioning of the BGA device 1 in the receiving space 210. The BGA device 1 is then pressed toward the pogo pins 22 to ensure electrical connection between the BGA device 1 and the testing circuit layout on the testing board 20 via the pogo pins 22 and the surface mount matrix 23.
Some of the drawbacks of the conventional contactor system 2 described beforehand are as follows:
1. When the BGA device 1 is pressed toward the pogo pins 22, scratching of the surface of the solder balls 12 by the pogo pins 22 is likely to occur. The solder material removed from one of the solder balls 12 can get trapped between an adjacent pair of the solder balls 12 and can result in short-circuiting, thereby leading to damage to the BGA device 1 and in a lower production yield.
2. As mentioned beforehand, exposed conductive contacts are present on the periphery of the insulating substrate 11 of the BGA device 1. After the BGA device 1 has been tested for defects and is removed from the socket 21, static electricity of as high as 600 to 800 volts is usually observed between the guide members 211 in the receiving space 210 and the exposed conductive contacts on the BGA device 1. The static electricity is discharged via the BGA device 1 since the socket 21 is made entirely from an insulator material, and can result in damage to the BGA device 1, which usually breaks down when subjected to a static electricity discharge of about 200 to 300 volts.
3. Due to the lengths of the pogo pins 22, the BGA device 1 experiences loss during high frequency testing.